1. Field of Invention
This invention relates to a method and apparatus for a hydrodynamic face seal between a rotating cylinder liner and a cylinder head in an internal combustion engine.
2. Description of Prior Art
This patent describes improved sealing methods and mechanisms between the cylinder liner and the cylinder head of a rotating sleeve engine or rotating liner engine (RLE). In a conventional engine, a seal between the cylinder head and stationary cylinder is typically obtained by compressing a head gasket between the head and the cylinder. Since the RLE has a rotating liner, an alternate means of sealing between the block and the liner is required.
Prior Art—The '872 Patent
The RLE is described in U.S. Pat. No. 6,289,872 issued Sep. 18, 2001 to applicant Dardalis. The '872 patent is incorporated by reference in this application. The RLE is a valved engine which provides a rotating liner, also called a sleeve, within the cylinder in order to reduce mechanical friction by maintaining hydrodynamic lubrication between the piston sealing means, which is typically one or more piston ring, and the rotating liner.
FIG. 1, which is FIG. 1 of the '872 patent, shows a first prior art embodiment. In the first embodiment, the '872 patent describes a set of pressure activated sealing devices 6 installed on the upper part of the rotating liner flange 4. The sealing devices 6 fit into a recess on the cylinder head 3 to prevent high pressure combustion gases from entering the space between the rotating liner 1 and the block 5. In FIG. 1, one prior art pressure activated seal is shown. This seal is a compression ring which provides a spring load against the outside of its groove machined into the cylinder head 3 and also provides a spring load against the sleeve flange 4.
FIG. 2, which is FIG. 5 of the '872 patent, shows a second prior art embodiment. In this second embodiment, a conical pressure activated sealing device is shown. A conical ring 21 fits on a conical groove 22 machined on the cylinder head 3. Like typical compression rings, that seal has an open end. The diameter of the conical ring when uncompressed is a little larger than the conical groove. Therefore, when forced into the groove 22, the spring force developed forces it against the outside wall of groove 22. Due to the inclined surfaces, a spring load develops between the lower surface of ring 21 and the upper flat surface of the rotating sleeve.
In a high combustion pressure variation of this embodiment, also shown in FIG. 2, an additional compression ring 23 is fitted on groove 24 machined on the flange of the rotating sleeve. Any combustion gasses that escape the main conical seal 21 are trapped by ring 23. Since ring 23 isolates the conical ring 21 from oil coming from the area between the sleeve and the cylinder, an additional oil supply 25 is provided to lubricate the conical seal as well as the interface of the upper part of the flange and cylinder head which acts as thrust bearing. A similar oil passage to 25 is provided on the opposite side and acts as oil return.
FIG. 3, which is FIG. 9 of the '872 patent, shows another prior art embodiment. In this embodiment, the bottom surface of the conical seal of FIG. 2 further includes a plurality of recessed inclined pads 46. The depth of these pads is exaggerated in FIG. 3 for clarity. In this embodiment, the pads machined along the compression ring 23 bottom sealing surface promote hydrodynamic lubricant pressure build up and help avoid metal to metal contact. The pads are imbedded in the sliding surface of ring in order to allow a tight sealing clearance in the rest of the surface.